linux-kernel - [PATCH] spi: loopback-test: Don't use %pK through printk

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Message-Id: <20250811-restricted-pointers-spi-v1-1-32c47f954e4d@linutronix.de>
Date: Mon, 11 Aug 2025 14:10:21 +0200
From: Thomas Weißschuh <thomas.weissschuh@...utronix.de>
To: Mark Brown <broonie@...nel.org>
Cc: linux-spi@...r.kernel.org, linux-kernel@...r.kernel.org, 
 Thomas Weißschuh <thomas.weissschuh@...utronix.de>
Subject: [PATCH] spi: loopback-test: Don't use %pK through printk

In the past %pK was preferable to %p as it would not leak raw pointer
values into the kernel log.
Since commit ad67b74d2469 ("printk: hash addresses printed with %p")
the regular %p has been improved to avoid this issue.
Furthermore, restricted pointers ("%pK") were never meant to be used
through printk(). They can still unintentionally leak raw pointers or
acquire sleeping locks in atomic contexts.

Switch to the regular pointer formatting which is safer and
easier to reason about.
There are still a few users of %pK left, but these use it through seq_file,
for which its usage is safe.

Signed-off-by: Thomas Weißschuh <thomas.weissschuh@...utronix.de>
---
 drivers/spi/spi-loopback-test.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/spi/spi-loopback-test.c b/drivers/spi/spi-loopback-test.c
index 7dd92deffe3fb1c2254777ce332c2eb52554aecf..e0b131aa29b62e9661be01b551e1260a7b0bbdfa 100644
--- a/drivers/spi/spi-loopback-test.c
+++ b/drivers/spi/spi-loopback-test.c
@@ -446,7 +446,7 @@ static void spi_test_dump_message(struct spi_device *spi,
 	int i;
 	u8 b;
 
-	dev_info(&spi->dev, "  spi_msg@%pK\n", msg);
+	dev_info(&spi->dev, "  spi_msg@%p\n", msg);
 	if (msg->status)
 		dev_info(&spi->dev, "    status:        %i\n",
 			 msg->status);
@@ -456,15 +456,15 @@ static void spi_test_dump_message(struct spi_device *spi,
 		 msg->actual_length);
 
 	list_for_each_entry(xfer, &msg->transfers, transfer_list) {
-		dev_info(&spi->dev, "    spi_transfer@%pK\n", xfer);
+		dev_info(&spi->dev, "    spi_transfer@%p\n", xfer);
 		dev_info(&spi->dev, "      len:    %i\n", xfer->len);
-		dev_info(&spi->dev, "      tx_buf: %pK\n", xfer->tx_buf);
+		dev_info(&spi->dev, "      tx_buf: %p\n", xfer->tx_buf);
 		if (dump_data && xfer->tx_buf)
 			spi_test_print_hex_dump("          TX: ",
 						xfer->tx_buf,
 						xfer->len);
 
-		dev_info(&spi->dev, "      rx_buf: %pK\n", xfer->rx_buf);
+		dev_info(&spi->dev, "      rx_buf: %p\n", xfer->rx_buf);
 		if (dump_data && xfer->rx_buf)
 			spi_test_print_hex_dump("          RX: ",
 						xfer->rx_buf,
@@ -558,7 +558,7 @@ static int spi_check_rx_ranges(struct spi_device *spi,
 		/* if still not found then something has modified too much */
 		/* we could list the "closest" transfer here... */
 		dev_err(&spi->dev,
-			"loopback strangeness - rx changed outside of allowed range at: %pK\n",
+			"loopback strangeness - rx changed outside of allowed range at: %p\n",
 			addr);
 		/* do not return, only set ret,
 		 * so that we list all addresses
@@ -696,7 +696,7 @@ static int spi_test_translate(struct spi_device *spi,
 	}
 
 	dev_err(&spi->dev,
-		"PointerRange [%pK:%pK[ not in range [%pK:%pK[ or [%pK:%pK[\n",
+		"PointerRange [%p:%p[ not in range [%p:%p[ or [%p:%p[\n",
 		*ptr, *ptr + len,
 		RX(0), RX(SPI_TEST_MAX_SIZE),
 		TX(0), TX(SPI_TEST_MAX_SIZE));

---
base-commit: 8f5ae30d69d7543eee0d70083daf4de8fe15d585
change-id: 20250811-restricted-pointers-spi-393d0b85c76b

Best regards,
-- 
Thomas Weißschuh <thomas.weissschuh@...utronix.de>